ServiceVerificationHandler does not record failure if service missing dependencies has no immediateUnavailableDependencies

ServiceVerificationHandler will put an OperationContext into rollback only mode if any services it is tracking are failed or are missing dependencies. But, if none are failed, and none have immediate unavailable dependencies (ServiceController.getImmediateUnavailableDependencies()) then the context failure description is not set. This combination of rollback-only preventing op completion and no error message causes the OperationContext to treat the op as if context.completeStep() was not called, failing with JBAS014750: Operation handler failed to complete

We need a failure description for this case, even though we don't know what services were missing.

For 7.2 we should also look into how OperationContext treats this situation; i.e. avoid having the presence or absence of a failure description as part of the detection on completeStep() not being called.